CN105548770A - Pulse laser equivalent LET value calculating method for SOI device - Google Patents

Abstract

The invention relates to a pulse laser equivalent LET value calculating method for an SOI device, and the method comprises the following steps: carrying out the irradiation scanning of the SOI device after an SOI device silicon substrate is removed, and obtaining the incident laser energy when the SOI device generates a single-particle effect; calculating the energy transmissivity of laser passing through a buried oxide layer of the SOI device according to the refractive indexes of air, the buried oxide layer and silicon, the reflection and transmission coefficients of laser from air to the buried oxide layer, the reflection and transmission coefficients of laser from the buried oxide layer to air, the reflection and transmission coefficients of laser from the buried oxide layer to silicon and the reflection and transmission coefficients of laser from silicon to the buried oxide layer; calculating a light spot influence parameter according to the laser light spot radius when laser arrives at a sensitive region and the lateral size of the sensitive region; and determining a pulse laser equivalent LET value according to the incident laser energy, the energy transmissivity and the light spot influence parameter. The method can obtain the key index LET value of single-particle effect sensitivity of the device quickly and accurately at low cost.

Description

A kind of pulse laser equivalence LET value calculating method of SOI device

Technical field

The present invention relates to space radiation technical field, particularly relate to a kind of pulse laser equivalence LET value detection method of SOI device.

Background technology

Single particle effect is one of most important ionization radiation effect affecting device space reliability, serious threat spacecraft safe and reliable operation in-orbit.The assessment of device anti-single particle effect characteristic generally adopts Bevilac and proton precessional magnetometer to carry out.But due to the operation of the large-scale experiment such as heavy ion, proton precessional magnetometer device and the practical problems of operation, often cause the cycle of single particle effect evaluation test and cost significantly to improve, even seriously hinder the normal development of device and completing smoothly of space tasks.Relatively and accelerator large-scale experiment device, Pulse Laser Simulator part single particle effect research technique has accurate single particle effect room and time resolution characteristic, energy continuously adjustabe, "dead", need not vacuumize, simple operation, the features such as test efficiency is high, and cost is low.Thus pulse laser is at home and abroad obtained for as effective single particle effect assessment mode and applies widely, has become the effective means of single particle effect characteristic evaluation and protection Design checking.In recent years, all establish pul sed laser simulation single particle effect test unit both at home and abroad, define the device single particle effect susceptibility evaluation capacity quick, cost is low.

LET (LinearEnergyTransfer, linear energy transfer) value is one of key project technical indicator evaluating aerospace electron device single particle effect susceptibility.The physical mechanism bringing out device single particle effect due to pulse laser, heavy ion is incomplete same, and in actual tests, laser spot size after focusing is subject to the restrictions such as optical maser wavelength, focalizer, optical diffraction, and the ionization path width of laser is more much bigger than the ionization path width of heavy ion.In addition, along with the raising of device integration, device front metal layer is more and more intensive, the experimental technique of pulse laser front incident irradiance device is very limited, and the experimental technique of pulse laser back irradiation device is used widely, but for the situation of laser back irradiation device, the transmission of the sandwich construction meeting appreciable impact laser energy of device.These make accurately to calculate the correspondence equivalence LET value that pulsed laser energy brings out single particle effect, become the technical problem underlying that restriction pul sed laser simulation single particle effect test method is applied in engineering practice.

SOI (SilicononInsulator, the silicon in insulator substrates), compared with conventional bulk silicon device, is separated by one deck buried oxidation layer between device and substrate, and device is only manufactured in the very thin silicon fiml in top layer, as shown in Figure 1.In Fig. 1,101 is source region, and 102 is grid, and 103 is drain region, and 104 is oxygen buried layer, and 105 is substrate.STI (ShallowTrenchIsolation) is the shallow channel isolation area in soi structure technique.N refers to the N-shaped doped region in soi structure.The structure of this uniqueness makes SOI device not have the latch-up of conventional bulk silicon MOS (Metal-Oxide-Semiconductor, Metal-oxide-semicondutor) device, has good Radiation hardness.But because the structure of SOI device is different in the structure of conventional bulk silicon technology device, existing relevant pulse laser equivalence LET value calculating method is set up based on typical body silicon technology device architecture, and when being applied to SOI device, accuracy is lower.

Summary of the invention

Based on this, be necessary for the lower problem of prior art accuracy, a kind of pulse laser equivalence LET value detection method of SOI device is provided.

A pulse laser equivalence LET value detection method for SOI device, comprises the following steps:

After removal SOI device silicon substrate, irradiation scanning is carried out to SOI device, obtains the incident laser energy of SOI device generation single particle effect;

According to the refractive index of air, oxygen buried layer and silicon, the reflection and transmission coefficients of laser from air to oxygen buried layer, the reflection and transmission coefficient from oxygen buried layer to air, the reflection and transmission coefficients from oxygen buried layer to silicon and the reflection and transmission coefficients from silicon to oxygen buried layer, calculate the energy transmission rate of laser through the oxygen buried layer of SOI device;

Lateral dimension according to laser facula radius during arrival sensitive volume and sensitive volume calculates hot spot affecting parameters;

According to described incident laser energy, energy transmission rate and hot spot affecting parameters determination pulse laser equivalence LET value.

The pulse laser equivalence LET value detection method of above-mentioned SOI device, by carrying out irradiation scanning to the SOI device removing silicon substrate, calculate the incident laser energy of SOI device, laser passes energy transmission rate and the hot spot affecting parameters of the oxygen buried layer of SOI device, and according to described incident laser energy, energy transmission rate and hot spot affecting parameters determination pulse laser equivalence LET value, the method may be used for space flight, in aviation and ground electronic system SOI device pul sed laser simulation single particle effect test assessment in, fast, low cost, more adequately obtain the key index LET value of device single particle effect susceptibility.

Accompanying drawing explanation

Fig. 1 is SOI junction composition;

Fig. 2 is the method schematic diagram of prior art;

Fig. 3 is the pulse laser equivalence LET value calculating method process flow diagram of SOI device of the present invention;

Fig. 4 is the SOI device schematic diagram that substrate is removed in the incidence of laser back;

Fig. 5 is that laser passes oxygen buried layer generation multiple-beam interference schematic diagram;

Fig. 6 is the modulation variation schematic diagram of transmissivity with oxygen buried layer thickness of 800nm laser;

Fig. 7 is the one dimension schematic diagram of the laser facula covering single particle effect sensitive volume of energy Gaussian distribution.

Embodiment

Be described below in conjunction with the embodiment of accompanying drawing to the pulse laser equivalence LET value calculating method of SOI device of the present invention.

As shown in Figure 2, existing pulse laser equivalence LET computing method are for typical body silicon technology device, under the test method of laser back irradiation device, consider energy attenuation and the accumulation of pulse laser transmitting procedure in chip substrate material, the wiring of analysis device front metal and substrate inside surface reflect the impact caused on laser multiple oscillation, calculate sensitive area inner to the contributive all pulsed laser energy values of single particle effect.Then equivalent LET is calculated according to the equivalence principle of laser energy and heavy ion LET value.In Fig. 2,201 is device back, and 202 is laser beam, and 203 is silicon substrate, and 204 is active area, and 205 is laser focal plane, and 206 is device front, and 207 is passivation layer, and 208 is metal level.

The technical scheme of prior art is set up based on typical body silicon technology device architecture, the structure of SOI device is different from the structure of typical body silicon technology device, thus inapplicable for this technology of SOI device.One large feature of prior art considers the repeatedly concussion reflection of laser in device substrate, but it calculates the ideal conditions based on Laser Transmission and device, and parameter more difficult measurement in actual applications involved in computation process.Along with the reduction of device technology size, the size of laser facula, much larger than the size of single particle effect sensitizing range, in the calculating of pulsed laser energy equivalence LET, thus need the impact considering laser spot size, but prior art is not considered.

For solving the problem, the invention provides a kind of pulse laser equivalence LET value calculating method.As shown in Figure 3, described pulse laser equivalence LET value calculating method can comprise the following steps:

S1, after removal SOI device silicon substrate, carries out irradiation scanning to SOI device, obtains the incident laser energy of SOI device generation single particle effect;

Similar with the process of Laser Transmission shown in Fig. 2, pulse laser back incident irradiance SOI device.Because SOI exists air/Si (silicon) substrate, Si substrate/SiO ₂the interface of different mediums such as (silicon dioxide), can there is reflex in laser, then produce in Si substrate and repeatedly shake reflection in interface.The thickness of device Si substrate is generally hundreds of micron, and laser, through so thick Si, serious attenuation by absorption phenomenon can occur, and finally has a strong impact on the laser energy inciding device active region.Suppose that the projectile energy of laser is E0, order of reflection is n, and passing through the total energy loss after Si layer for i-th time is Δ Ei, i=1,2 ..., n, then final shoot laser energy is E0-Δ E2n.These make Laser energy transmission calculate and test process becomes complicated, are difficult to obtain accurate result.For the impact of Si substrate on incident laser energy, existing computing method are the ideal conditionss based on Laser energy transmission and device, and the parameter more difficult measurement in actual applications involved by computation process, the calculating of this paired pulses laser equivalence LET causes very large error.Therefore, before irradiation scanning is carried out to SOI device, SOI device silicon substrate can be removed, thus improve counting accuracy.SOI device silicon substrate is removed by etching.

XeF ₂(xenon difluoride) is a kind of working gas Si being carried out to commonly use in plasma etching, reactive ion etching.In etching, XeF ₂gas can be adsorbed on silicon face, even if under the condition not having external energy, and XeF ₂also can produce xenon and fluorine by Auto-decomposition, and fluorine at room temperature can carry out the etching of higher rate to silicon chip.XeF ₂the major advantage of etching is: first it is a kind of dry etching, and its etching reaction product all can be extracted by vacuum system, does not substantially etch pollution; Secondly this etching has very high Selection radio to many materials, such as silicon dioxide, silicon nitride, aluminium and photoresist etc., wherein XeF ₂all can up to 1000:1 to silicon dioxide etching selection ratio.The oxygen buried layer of SOI device is generally SiO ₂material.Therefore, XeF ₂have Si/SiO ₂the characteristic of very high etching selection ratio is highly suitable for etching the Si substrate removing SOI device.

Utilize XeF ₂the basic procedure that reactive ion etching removes SOI device Si substrate can comprise the steps:

First, by acid corrosion opening method, is broken a seal in SOI device back.For the method that common plastic packaging and Metal Packaging device generally adopt acid corrosion to break a seal.

Then, can casting glue be adopted to fill in the SOI device front through Kaifeng.XeF can be ensured in this way ₂in reactive ion etching process, device is fixed injury-free.

Finally, the SOI device through filling can be put into XeF ₂etch in reactive ion etching device, until SOI device substrate silicon material all etches removal, expose oxygen buried layer silica surface.

As Fig. 4 signal, laser back incident irradiance removes the SOI device after Si substrate, completely avoid the effect such as reflection, refraction, attenuation by absorption of substrate to laser incidence.In the diagram, 401 represent laser, and 402 is Si substrate, and 403 is oxygen buried layer, and 404 is active area, and 405 is epoxy resin.

For the test of Pulse Laser Simulator part single particle effect, the method for generally being tested by step-scan carries out irradiation scanning to whole test component, the final incident laser energy E obtaining device generation single particle effect ₀.Laser energy is measured by the laser energy meter being applicable to corresponding optical maser wavelength.

S2, according to the refractive index of air, oxygen buried layer and silicon, the reflection and transmission coefficients of laser from air to oxygen buried layer, the reflection and transmission coefficient from oxygen buried layer to air, the reflection and transmission coefficients from oxygen buried layer to silicon and the reflection and transmission coefficients from silicon to oxygen buried layer, calculate the energy transmission rate of laser through the oxygen buried layer of SOI device;

Particularly, calculating laser can comprise through the step of the energy transmission rate of the oxygen buried layer of SOI device:

Calculate the phase differential of two bundle adjacent transmissive light beams;

According to the complex amplitude of the total transmitted light beam of described phase difference calculating;

According to the transmission coefficient of the complex amplitude of transmitted light beam and the magnitude determinations laser of incident beam;

Described energy transmission rate is calculated according to described transmission coefficient.

As shown in Figure 4, for the SOI device removed after Si substrate, oxygen buried layer is incided at laser back (such as, can be SiO ₂) surface, incide device active region through after oxygen buried layer.According to Laser Transmission principle, owing to there are air/oxygen buried layer and oxygen buried layer/Si two kinds of interfaces, can there is multiple reflections, refraction effect in laser on its transmission path.Thickness due to oxygen buried layer is generally hundreds of nanometer, is generally less than the optical maser wavelength that institute's laser test adopts, and the laser beam thus through oxygen buried layer can produce multiple-beam interference, and the transmissivity of oxygen buried layer to laser energy has modulating action.Pulse laser equivalence LET is calculated and first should determine the impact of oxygen buried layer on laser energy, namely calculate the energy transmission rate T of laser through oxygen buried layer.

Radiation mode due to the test of laser analog single particle effect is the incident device back side of laser vertical, also only considers normal incidence situation when calculating laser passes the transmissivity of oxygen buried layer.As shown in Figure 5, if the refractive index of air 501, oxygen buried layer 502 and Si503 is respectively n ₀, n, n _sif the reflection and transmission coefficients of laser from air to oxygen buried layer is r ₁and t ₁, the reflection and transmission coefficient in the other direction from oxygen buried layer to air is r ' ₁with t ' ₁, r ₁=-r ' ₁; Reflection and transmission coefficients from oxygen buried layer to Si is r ₂and t ₂, the reflection and transmission coefficients from Si to oxygen buried layer is r ' ₂and t' ₂, r ₂=-r ' ₂, oxygen buried layer thickness is d.The amplitude of incident beam is E _0i, omit common initial phase, the phase differential of two bundle adjacent transmissive light beams is:

$\mathrm{\δ}=2kd=\frac{4\mathrm{\π}nd}{\mathrm{\λ}}---\left(1\right)$

In formula, k is the wave vector of laser light wave transmissions, and numerical values recited equals 2 π n/ λ, and λ is laser wavelength in a vacuum.Total transmitted light beam complex amplitude is the amplitude sum of each transmitted light beam:

$\begin{array}{c}{E}_{0t}=E_{01t}+E_{02t}+E_{03t}+\mathrm{...}\\ =\frac{t_1{t}_2}{1+r_1{r}_2\exp \left(i\mathrm{\δ}\right)}{E}_{0i}\end{array}---\left(2\right)$

Then the transmission coefficient of laser is:

$t=\frac{E_{0t}}{E_{0i}}=\frac{t_1{t}_2}{1+r_1{r}_2\exp \left(i\mathrm{\δ}\right)}---\left(3\right)$

According to Fresnel formula:

$T=\frac{n_2}{n_1}|t{|}^2---\left(4\right)$

Transmissivity T is:

$T=\frac{n_S}{n_0}\frac{|t_1{t}_2{|}^2}{|1+r_1{r}_2\exp \left(i\mathrm{\δ}\right){|}^2}=\frac{n_S}{n_0}\frac{{\left(t_1{t}_2\right)}^2}{1+{\left(r_1{r}_2\right)}^2+2r_1{r}_2\cos \left(\mathrm{\δ}\right)}---\left(5\right)$

And will respectively penetrate coefficient r ₁, r ₂with transmission coefficient t ₁, t ₂substitute into formula (5) and can net result be obtained:

$T=\frac{n_S}{n_0}|t{|}^2=\frac{4n_0{n}_S}{{(n_0+n_S)}^2{\cos }^2\left(\frac{\mathrm{\δ}}{2}\right)+{(\frac{n_0{n}_S}{n}+n)}^2{\sin }^2\left(\frac{\mathrm{\δ}}{2}\right)}---\left(6\right)$

For the common wavelength of laser analog single particle effect for 800nm laser, the refractive index of air is 1, the refractive index of oxygen buried layer is the refractive index of 1.5, Si is 3.65, the laser calculated through oxygen buried layer transmissivity with oxygen buried layer thickness modulation variation as shown in Figure 6.

S3, the lateral dimension according to laser facula radius during arrival sensitive volume and sensitive volume calculates hot spot affecting parameters;

Along with the reduction of device technology size, for sub-micron so that the device of less process, the size of laser facula is much larger than the size of single particle effect sensitive volume.Such as, SOISRAM (the StaticRandomAccessMemory of certain typical 90nm technique, static RAM), single-particle inversion sensitive volume is of a size of 0.2 micron, and the impact of the size-constrained factor such as diffraction in optical maser wavelength and Laser Transmission process of Laser Focusing hot spot, be such as the laser of 590nm for conventional wavelength, the diameter of focal beam spot is greater than 1 micron.Thus must consider the impact of laser spot size on laser energy deposition in the calculating of pulsed laser energy equivalence LET, represent with light spot affecting parameters F.

Fig. 7 is the one dimension schematic diagram that laser facula covers single particle effect sensitive volume, and the energy distribution of laser facula is Gaussian distribution in the horizontal.In the figure 7,701 represent single particle effect sensitive volume, and 702 represent the region that laser facula covers, and 703 represent Si active area, and 704 represent SiO ₂oxygen buried layer.If the center of laser facula is consistent at the center of single particle effect sensitive volume, then the Laser beam energy distribution function of the two dimension in single particle effect sensitive volume is:

$E(x,y)=\frac{2E}{{\mathrm{\π\ω}}^2}\exp \left(\frac{-2(x^2+y^2)}{{\mathrm{\ω}}^2}\right)---\left(7\right)$

In formula, E is the energy of the laser pulse incided in sensitive volume, x and y is the coordinate of laser facula in sensitive volume, ω is laser facula radius when arriving sensitive volume, because the thickness of sensitive volume is very little, such as the sensitive volume thickness of typical 90nmSOI device is about 70nm, and spot size change in the vertical can be ignored, and thus ω is constant.In sensitive volume, effective laser energy is exactly the integration of Laser beam energy distribution in sensitive volume:

$E_{sv}={\∫}_{-\frac{a}{2}}^{\frac{a}{2}}{\∫}_{-\frac{b}{2}}^{\frac{b}{2}}\frac{2E}{{\mathrm{\π\ω}}^2}\exp \left(\frac{-2(x^2+y^2)}{{\mathrm{\ω}}^2}\right)dxdy---\left(8\right)$

In formula, a and b is the lateral dimension of sensitive volume, generally determine according to the technique of device, such as CMOS (ComplementaryMetalOxideSemiconductor, complementary metal oxide semiconductor (CMOS)) the sensitive volume size of SRAM single-particle inversion is by NMOS (N-Metal-Oxide-Semiconductor, N-type Metal-oxide-semicondutor) and the size of PMOS (P-Metal-Oxide-Semiconductor, P type Metal-oxide-semicondutor) drain region.Above formula can be written as:

E _sv＝E·F(9)

Then spot size on the parameter F of the impact of laser energy deposition is:

$\begin{array}{c}F=\frac{E_{sv}}{E}={\∫}_{-\frac{a}{2}}^{\frac{a}{2}}{\∫}_{-\frac{b}{2}}^{\frac{b}{2}}\frac{2}{{\mathrm{\π\ω}}^2}\exp \left(\frac{-2(x^2+y^2)}{{\mathrm{\ω}}^2}\right)dxdy\\ =\frac{2}{{\mathrm{\π\ω}}^2}erf\left(\frac{a}{\sqrt{2}\mathrm{\ω}}\right)\·erf\left(\frac{b}{\sqrt{2}\mathrm{\ω}}\right)\end{array}---\left(10\right)$

For the laser that above-mentioned wavelength is 590nm, laser facula radius is 0.83 micron, and the lateral dimension of single-particle inversion sensitive volume is 0.2 micron, then consider that spot size affects laser energy deposition, the result of calculation of parameter F is about 0.034.Can find out, after considering spot size, effective laser deposition energy is original 3.4%, otherwise, if do not consider the impact of laser spot size, the calculating of paired pulses laser energy equivalence LET is produced great error.

S4, according to described incident laser energy, energy transmission rate and hot spot affecting parameters determination pulse laser equivalence LET value.

Definition according to LET value:

$LET=\frac{1}{\mathrm{\ρ}}\·\frac{dE}{dx}---\left(11\right)$

ρ is the density of incident semiconductor material.Pulse laser enters Si active area through oxygen buried layer, under laser energy linear absorption mechanism, absorbs a photon and produces an electron hole pair, and laser energy obeys Beer law with the attenuation law of incident degree of depth x, then pulse laser equivalence heavy ion LET value is:

$ELET=\frac{{\mathrm{\λE}}_{ion}}{\mathrm{\ρ}hc}{\mathrm{\αE}}_{0}TF\exp (-\mathrm{\α}x)---\left(12\right)$

Therefore, in the sensitive volume of device, pulse laser equivalence LET value is:

$ELET=\frac{{\mathrm{\λE}}_{ion}}{\mathrm{\ρ}hcl}{E}_{0}TF(1-\exp (-\mathrm{\α}l\left)\right)---\left(13\right)$

In formula, ELET is described pulse laser equivalence LET value, and λ is pulse laser wavelength, E _ionattach most importance to ion excitation pair of electrons hole to required energy, and ρ is the density of incident semiconductor material, and h is Planck constant, and c is the light velocity, and l is single particle effect sensitive volume thickness, E ₀for inciding the laser energy on oxygen buried layer surface, T is the transmissivity of oxygen buried layer, and F is hot spot affecting parameters, and α is the absorption coefficient of laser in silicon active area.

It should be noted that, the influence factor such as pulse width, nonlinear optical absorption effect of pulse laser is controlled at test needs and is not enough to affect above computing method.The span of the wavelength X of pulse laser is 250nm ~ 1130nm, and oxygen buried layer material includes but not limited to SiO ₂material.

Compared with existing technical scheme, the present invention establishes and utilizes XeF ₂the pulse laser equivalence LET computing method being applicable to SOI device structure of reactive ion etching silicon:

(1) XeF is adopted ₂the method of reactive ion etching removes SOI device Si substrate, make to be directly incident on oxygen buried layer surface during the irradiation of pulse laser back, avoid the repeatedly concussion reflection process of laser in device substrate, pulse laser equivalence LET is calculated and greatly simplifies, add the accuracy of final calculation result.Simultaneously owing to eliminating the attenuation by absorption effect of substrate to laser energy, the laser wavelength range that can be used for the test of pul sed laser simulation single particle effect is significantly increased.

(2) analyze oxygen buried layer to the impact of transmission laser energy, determine the computing method of transmissivity, obtain laser through the result of energy transmission rate after oxygen buried layer by oxygen buried layer thickness modulation variation.

(3) analyze laser spot size to the impact of laser energy bringing out single particle effect, determine the computing method of hot spot affecting parameters F, obtaining spot size parameter affects result to effective laser energy.

Each technical characteristic of the above embodiment can combine arbitrarily, for making description succinct, the all possible combination of each technical characteristic in above-described embodiment is not all described, but, as long as the combination of these technical characteristics does not exist contradiction, be all considered to be the scope that this instructions is recorded.

The above embodiment only have expressed several embodiment of the present invention, and it describes comparatively concrete and detailed, but can not therefore be construed as limiting the scope of the patent.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.

Claims (9)

1. a pulse laser equivalence LET value detection method for SOI device, is characterized in that, comprise the following steps:

After removal SOI device silicon substrate, irradiation scanning is carried out to SOI device, obtains the incident laser energy of SOI device generation single particle effect;

According to the refractive index of air, oxygen buried layer and silicon, the reflection and transmission coefficients of laser from air to oxygen buried layer, the reflection and transmission coefficient from oxygen buried layer to air, the reflection and transmission coefficients from oxygen buried layer to silicon and the reflection and transmission coefficients from silicon to oxygen buried layer, calculate the energy transmission rate of laser through the oxygen buried layer of SOI device;

Lateral dimension according to laser facula radius during arrival sensitive volume and sensitive volume calculates hot spot affecting parameters;

According to described incident laser energy, energy transmission rate and hot spot affecting parameters determination pulse laser equivalence LET value.

2. the pulse laser equivalence LET value calculating method of SOI device according to claim 1, it is characterized in that, described oxygen buried layer includes but not limited to SiO ₂material.

3. the pulse laser equivalence LET value calculating method of SOI device according to claim 1, is characterized in that, before carrying out irradiation scanning to SOI device, further comprising the steps of:

Etching removes SOI device silicon substrate.

4. the pulse laser equivalence LET value calculating method of SOI device according to claim 3, is characterized in that, utilize XeF ₂reactive ion etching removes SOI device silicon substrate.

5. the pulse laser equivalence LET value calculating method of SOI device according to claim 4, is characterized in that, utilize XeF ₂the step that reactive ion etching removes SOI device silicon substrate comprises:

By acid corrosion opening method, is broken a seal in SOI device back;

Casting glue is adopted to fill in the SOI device front through Kaifeng;

SOI device through filling is put into XeF ₂etch in reactive ion etching device, until SOI device substrate silicon material all etches removal, expose oxygen buried layer silica surface.

6. the pulse laser equivalence LET value calculating method of SOI device according to claim 1, it is characterized in that, calculating laser comprises through the step of the energy transmission rate of the oxygen buried layer of SOI device:

Calculate the phase differential of two bundle adjacent transmissive light beams;

According to the complex amplitude of the total transmitted light beam of described phase difference calculating;

According to the transmission coefficient of the complex amplitude of transmitted light beam and the magnitude determinations laser of incident beam;

Described energy transmission rate is calculated according to described transmission coefficient.

7. the pulse laser equivalence LET value calculating method of SOI device according to claim 6, it is characterized in that, the step calculating described transmissivity according to described transmission coefficient comprises:

Energy transmission rate according to following formulae discovery:

$T=\frac{n_S}{n_0}\frac{{\left|t_1{t}_2\right|}^2}{{|1+r_1{r}_2\exp \left(i\mathrm{\δ}\right)|}^2}=\frac{n_S}{n_0}\frac{{\left(t_1{t}_2\right)}^2}{1+{\left(r_1{r}_2\right)}^2+2r_1{r}_{2}cos\left(\mathrm{\δ}\right)},$

In formula, T is described energy transmission rate, n _sand n ₀be respectively the refractive index of silicon and air, t ₁for the transmission coefficient of laser from air to oxygen buried layer, t ₂for the transmission coefficient of laser from oxygen buried layer to silicon, δ is described phase differential, and i is the quantity of adjacent projections light beam, r ₁for the reflection coefficient of laser from air to oxygen buried layer, r ₂for the reflection coefficient of laser from oxygen buried layer to silicon.

8. the pulse laser equivalence LET value calculating method of SOI device according to claim 1, is characterized in that, the step calculating hot spot affecting parameters according to the lateral dimension of laser facula radius when arriving sensitive volume and sensitive volume comprises:

Hot spot affecting parameters according to following formulae discovery:

$\begin{array}{c}F=\frac{E_{SV}}{E}=\underset{-\frac{a}{2}}{\overset{\frac{a}{2}}{\∫}}\underset{-\frac{b}{2}}{\overset{\frac{b}{2}}{\∫}}\frac{2}{{\mathrm{\π\ω}}^2}\exp \left(\frac{-2(x^2+y^2)}{{\mathrm{\ω}}^2}\right)dxdy\\ =\frac{2}{{\mathrm{\π\ω}}^2}erf\left(\frac{a}{\sqrt{2}\mathrm{\ω}}\right)erf\left(\frac{b}{\sqrt{2}\mathrm{\ω}}\right)\end{array},$

In formula, F is described hot spot affecting parameters, and E is the energy of the laser pulse incided in sensitive volume, E _sVfor laser energy effective in sensitive volume is exactly the integration of Laser beam energy distribution in sensitive volume, a and b is the lateral dimension of sensitive volume, and ω is laser facula radius when arriving sensitive volume.

9. the pulse laser equivalence LET value calculating method of SOI device according to claim 1, is characterized in that, the step calculating pulse laser equivalence LET value according to described energy transmission rate and hot spot affecting parameters comprises:

Pulse laser equivalence LET value according to following formulae discovery

$ELET=\frac{{\mathrm{\λE}}_{ion}}{phcl}{E}_{0}TF(1-\exp (-\mathrm{\α}l\left)\right),$

In formula, ELET is described pulse laser equivalence LET value, and λ is pulse laser wavelength, E _ionattach most importance to ion excitation pair of electrons hole to required energy, and ρ is the density of incident semiconductor material, and h is Planck constant, and c is the light velocity, and l is single particle effect sensitive volume thickness, E ₀for inciding the laser energy on oxygen buried layer surface, T is the transmissivity of oxygen buried layer, and F is hot spot affecting parameters, and α is the absorption coefficient of laser in silicon active area.